A mortgage is a loan a family/person can get from the bank/mortgage lender or financial institute to buy/refinance a house. There is a certain percentage that must be paid before being able to get a mortgage out. A mortgage is paid in instalments, usually with interest. If unable to be paid, the lender can take possession of the property.
You need to send a mortgage application to the lender you are loaning money from and the percentage they are paying. Set a term to pay the money by and the interest rate.